A number of desktop camera-projector systems exist. Positioned above a desk or work surface, these systems allow a user to select functions to be performed by selecting items within the field of view of the camera. A video camera or scanner captures images of hardcopy documents on the work surface. Feedback information may be displayed to the user via the projector. Available functions include calculation and translation of data included within documents within the field of view of the camera. One such system is described in European Application EP-A-495,622.
European Application EP-A-622,722 describes another camera-projector system. This system generates new documents by capturing information contained within a hardcopy document including text and/or images. The system captures the information using a camera-projector system directed at the hardcopy document as it resides on a desk. The system also works in conjunction with a printer or copier. The system determines which functions are to be performed based upon input from the user captured by the camera. User input may include pointing at the relevant data or tapping on the surface of the hardcopy document to point out the relevant text or images. The system provides user feedback by projecting an image onto the work surface or on to the hardcopy document itself.
The system described in European Application EP-A-622,722 suffers from a number of disadvantages. The system's projector and camera are large and bulky and must be fixedly mounted. This makes the system difficult to set-up and difficult to move. Many potential users find it impossible to set-up over their existing desks. Furthermore, the camera's field of view is limited and difficult to change. The system also makes it difficult to change the camera zoom. The system's projector has limited resolution and range and a trade-off is required between the two. This is a disadvantage because some user applications, like fine sketching and handwriting, require high resolution per square inch while other user applications, like architectural visualization, require a large surface area and lower resolution per square inch. Any given projection must sacrifice one for the other, either size for resolution or vice versa. Once one has been chosen, modifying that choice is difficult.
Prior camera-projector systems tend to produce low resolution images because of the video cameras used. Text recognition programs within scanners perform poorly when presented with these low resolution images. Given these low resolution images to print, printers produce poor quality documents. One possible solution to these problems when the user is working with relatively small portions of a source document is to zoom the system camera to focus only on the portion of interest. This solution requires that the user be able to control the camera. A user could control the camera by manually adjusting the camera zoom before selecting portion of interest. This is an extra step and requires extra controls and a monitor of some sort so that the user can see "through the camera." These camera controls are independent of display size and resolution. If the user wishes to adjust these other steps and controls are necessary and require choosing between display size and resolution.